Device to puncture wing environmental seals and reduce deployment force

ABSTRACT

A puncturing feature is provided on the deployable wings of a precision guidance kit of a rocket to facilitate breaking through the wing slot seal that protecting the wings prior to deployment. The puncturing feature may be a sharp region on the leading edge near the wing tip that first contacts the wing slot seal. The puncturing feature may be a sharp edge extended along the leading edge of the wing to provide a cutting action as the wing passes through the wing slot seal.

BACKGROUND

Aerial rockets and missiles which include folded, deployable guidance wings, have been in use for many years. Some examples include the Hydra 70 family of WAFAR (Wrap-Around Fin Aerial Rocket) and APKWS® laser guided missile. For many such weapons, the guidance wings are folded in a stowed configuration within the main fuselage until the weapon is launched, at which point the wings deploy outward through slots provided in the fuselage.

In one such example, the APKWS precision guidance kit is added to a 2.75″ (70 mm) diameter rocket such as the Hydra-70 (MK66). The APKWS has wings that start in a stowed position thus allowing the munition to fit inside existing launching tubes. When the rocket is fired it begins to spin to improve stability. Firing of the rocket awakens the APKWS system. Once the control system is initiated and operational, the four control surfaces, known as flaperons, are commanded to rotate to the zero position, thus unlatching them from their stow latch. Once unlatched, the centrifugal force of the spinning rocket causes the wings/control surfaces to pivot about a fixed point near their root and deploy outwards to approximately a 30° angle from the munition centerline.

In some cases, the wing slots are covered by frangible seals which protect the interior of the missile from moisture and debris during storage, transport, and handling. For example, the APKWS has environmental seals covering the four wing slots to protect the internal components. Examples of wing slot seals disposed on an APKWS are disclosed in U.S. Pat. No. 8,895,908, assigned to the same assignee as the present application, the entire disclosure of which is hereby incorporated by reference. In these cases the guidance wings must be deployed with sufficient initial force to enable them to penetrate the seals.

However, there is a practical limit to how rapidly a missile can be spun. In one example, the average centrifugal force on the tip of a guidance wing at the beginning of deployment is only approximately 7.7 pounds at the minimum spin rate. This amount of centripetal energy may not be sufficient by itself to enable the wings to burst through the frangible slot covers. As a result, some weapons that include deployable folded guidance wings and frangible wing slot covers have demonstrated a tendency for the guidance system to fail due to a lack of proper guidance wing deployment.

One approach to address this problem is the addition of a wing deployment force initiator, which assists the deployment of the guidance wings by providing an initial burst of energy to help the wings break through the frangible covers. In one such design, the wing deployment initiator uses explosives to push the wings through the frangible covers. However, this approach can be undesirable due to the violent forces produced by the explosives and due to concerns about the safety and the long-term chemical stability of the explosives during storage of the weapon.

Another approach is to provide a torsion spring wing deployment initiator which provides additional force to push the wings outward a small amount. One such torsion spring wing deployment initiator is described in U.S. Pat. No. 8,868,329 assigned to the same assignee as the present application, the entire disclosure of which is hereby incorporated by reference. This approach avoids the problems of using explosives. An alternative approach is a compression spring wing deployment initiator. One such compression spring wing deployment initiator is described in U.S. Pat. No. 8,754,352, assigned to the same assignee as the present application, the entire disclosure of which is hereby incorporated by reference.

However, there is only very limited space available for a wing deployment initiator to occupy. Also, for some applications, the weight of the deployment initiator should be as low as possible. Therefore, it is desirable to provide a mechanical wing deployment initiator which can provide sufficient force to enable the guidance wings to break through the frangible covers while also fitting within the available space and remaining sufficiently light in weight.

For certain applications, a more compact and less complex solution would be desirable, since the reduced complexity would lower the cost of production and would decrease the likelihood of failure if the mechanism did not perform as intended.

BRIEF SUMMARY

In one embodiment, an aerial projectile, such as a missile or rocket, is disclosed having a fuselage, at least one wing slot formed in the fuselage and a wing slot seal covering each of the at least one wing slot. A guidance wing in a stowed position within each of the at least one wing slot prior to deployment of the wing, includes a puncturing feature formed on a leading edge of the wing. The puncturing feature is configured to break through the wing slot seal during deployment of the wing from the stowed position. In a further embodiment a precision guidance kit is an assembly that is configured to couple to a rocket, such as the Hydra rocket, and comprises wings, slot seal, and related components.

In one embodiment, the puncturing feature is a small sharp region on the leading edge near the wing tip that first contacts the wing slot seal. In one embodiment, the small sharp feature is formed by a sharp point.

In one embodiment, the puncturing feature is a sharp edge extended along the leading edge of the wing to provide a cutting action as the wing passes through the wing slot seal. In one embodiment, the extended sharp edge puncturing feature has serrations to increase the cutting action.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an aerial rocket or missile shown with the wings deployed with one embodiment of the wing slot seal puncturing feature of the present disclosure.

FIG. 2 is a cross sectional view of the wings of an aerial rocket or missile in a stowed position within the fuselage.

FIG. 2A is a diagram of one embodiment of the wing slot seal puncturing feature of the present disclosure.

FIG. 2B is a diagram of one embodiment of the wing slot seal puncturing feature of the present disclosure.

FIG. 2C is a diagram of one embodiment of the wing slot seal puncturing feature of the present disclosure.

FIG. 3 is an end view of a wing stowed within fuselage an aerial rocket or missile showing the side profile of one embodiment of the puncturing feature extending beyond the rounded edge of the wing.

FIG. 4 is a perspective view of an aerial rocket or missile showing one embodiment of the wing slot seal puncturing feature of the present disclosure has broken through a burst seam the wing slot seal.

Further features as well as the structure and operation of various embodiments are described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements.

DETAILED DESCRIPTION

In one embodiment a puncturing feature is provided on the wing of the rocket to facilitate breaking through the wing slot seal. In one embodiment, the puncturing feature is small sharp region on the leading edge near the wing tip. This is the region of the wing that first contacts the wing slot seal. In one embodiment, the small sharp feature has a sharp point that will puncture the wing slot seal just like a bird's egg tooth.

In one embodiment, the puncturing feature is a sharp edge extended along the leading edge of the wing to provide a cutting action as the wing passes through the wing slot seal. In one embodiment the additional length of the sharp edge would slice the wing slot seal as the wing passes through just like a knife blade. In one embodiment, the extended sharp edge puncturing feature has serrations to increase the cutting action.

The puncturing feature is an improvement over the prior art deployment initiators by reducing the amount of force required by the wing to puncture the wing slot seal and improve wing deployment reliability. In one embodiment, the puncturing feature reduces the deployment force enough where the wings can deploy reliably without the need for an additional mechanical deployment initiator, thereby avoiding the increased weight and cost of the prior art solutions.

The puncturing feature could be a machined feature of the wing or it could be a separate part that is then attached to the wing. The puncturing feature may to be made from a material with structural hardening such as steel, stainless steel and tungsten carbide. In one example, metal hardness may be specified by ASTM E18, which is a standard that defines the Rockwell hardness test method for metallic materials. In one embodiment, a metallic material that has a Rockwell C-scale hardness of 35 or greater may be specified. In one embodiment, the puncturing feature may be made with fine grain properties that it can be sharpened to a keen edge, such as those meeting the test detailed in ASTM standard E112. However, other materials such as hard plastic, ceramic or glass could serve as the puncture and/or cutting feature.

FIG. 1 is a perspective view of one embodiment of an aerial rocket or missile 10 that include guidance wings 12 which are typically folded within the main fuselage 14 in a stowed configuration until the weapon is launched, at which point the wings 12 are released and deployed through wing slots 16. FIG. 1 illustrates the missile 10 having just been launched with its guidance wings 12 deployed. The wing slots 16 in these missiles 10 are covered by frangible environmental cover seals 18, which protect the interior of the missile from dirt and debris before missile launch. Deployment of the guidance wings 12 requires sufficient initial force to enable the wings 12 to break through the frangible cover seals 18. The wings 12 include puncturing feature 20 on the leading edge near the wing tip to break through the wing cover seals 18. The dashed line 17 shows where the wing 12 has broken through the wing slot seal 18.

According to one embodiment, the wings 12, wing slots 16, and frangible cover seals 18 along with guidance and navigation electronics are integrated into a precision guidance kit 25. The precision guidance kit 25 in one example is contained within a section of the fuselage 27 with connectors (not shown) such that the precision guidance kit 25 is secured between the rocket section and the warhead section. In one example the precision guidance kit 25 is screwed onto the rocket and the warhead. The precision guidance kit 25 is coupled to a rocket in order to convert the rocket into a precision guided projectile. One example of this is the APKWS precision guidance kit.

FIG. 2 is a cross sectional view of the wings 12 in a stowed position within the fuselage 14. The wings 12 include the puncturing feature 20 on the leading edge near the wing tip. FIG. 2A shows one embodiment of the puncturing feature 20 being configured as a sharp point 22 on the leading edge of the wing 12. FIG. 2B shows one embodiment of the puncturing feature 20 configured as a sharp edge 24 extending along the leading edge of the wing 12. FIG. 2C shows one embodiment of the puncturing feature 20 configured as a sharp edge with serrations 26. In the stowed position, the puncturing feature 20 is below the wing slot seal 18.

FIG. 3 is an end view of a wing 12 stowed within fuselage 14 showing the side profile of the puncturing feature 20 extending beyond the rounded edge of the wing.

FIG. 4 is a perspective view of one embodiment in which the wing slot seal 18 includes a burst seam 30. The burst seam 30 is configured be aligned with the puncturing feature 20 so as to allow the guidance wing 12 to separate and pass through the burst seam 30 during deployment of the guidance wing 12. In one embodiment, the wing slot seal 18 is formed of a barrier sheet and an adhesive layer on inner surface of the barrier sheet. The adhesive layer is configured to secure the barrier sheet to the region of fuselage 14 surrounding the wing slot 16. In one embodiment, the adhesive layer provides an adhesive strength which is sufficient to maintain the barrier sheet in position over the wing slot 16 while the guidance wing 12 breaks through the barrier sheet at the burst seam 30 facilitated by the puncturing feature 20 during deployment of the guidance wing 12. The burst seam 30 is configured to close and resist penetration when a force is applied to the barrier layer from outside of the rocket or missile 10.

In one embodiment, the wing slot seal provides a frangible barrier against exposure of internal components of a rocket or missile to external contaminants, while enabling deployment of a wing stored within the rocket or missile simply by bursting of the wing through the frangible seal. The seal is strong enough to resist rupture or dislodgement from the exterior due to normal transport and handling of the missile, while at the same time presenting minimum resistance to penetration from the interior when the guidance wings are deployed by bursting through the seal.

In one embodiment, the wing slot seal is a thin, flexible sheet which can be adhered to a surface of the fuselage of the rocket or missile so as to cover a wing slot. In embodiments, the seal is sufficiently thin so as not to exceed the diameter of “bore riders” of the missile which define the maximum diameter of the missile, and which support the missile when resting within a cylindrical launching or transporting tube.

In one embodiment, the thin, flexible sheet includes an outer layer and an inner layer. Both of the layers may be made of a nickel alloy, and in some of these embodiments one layer is made of half-hard nickel sulfamate, while the other layer is made of fully hard nickel sulfamate. The inner layer includes at least one burst seam which assists the wing in breaking through the seal for deployment. The flexible sheet may be curved according to the cylindrical shape of the rocket or missile, and the two layers are stiff, although flexible, so that inward deformation due to pressure applied from outside the rocket or missile tends to force the edges of the burst seam together, thereby resisting the applied force, while outward deformation caused by the wing pressing against the seal from within the rocket or missile tends to force the edges of the burst seam apart, so that the wing passes through the cut or cuts in the inner layer and is only required to break through the outer layer.

In one embodiment, the flexible sheet is resilient or “springy,” so that once the wing is deployed, portions of the flexible sheet which lie against the deployed wing remain substantially flush against the wing, while portions of the flexible sheet which are not adjacent to the deployed wing tend to spring back into place and close the opening made in the frangible seal. The effect of the frangible seal on the aerodynamics of the rocket or missile is thereby minimized.

While the present invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms and details may be made without departing from the spirit and scope of the present invention. It is therefore intended that the present invention not be limited to the exact forms and details described and illustrated, but fall within the scope of the appended claims. 

What is claimed is:
 1. An aerial projectile, comprising: a fuselage; at least one wing slot formed in the fuselage; a wing slot seal covering each of the at least one wing slot; and a guidance wing being in a stowed position within each of the at least one wing slot prior to deployment of the wing, the guidance wing having a puncturing feature formed on a leading edge of the wing, the puncturing feature being configured to break through the wing slot seal during deployment of the wing from the stowed position.
 2. The aerial projectile of claim 1, wherein the puncturing feature is formed proximate a tip of the wing.
 3. The aerial projectile of claim 1, wherein the puncturing feature is a sharp point.
 4. The aerial projectile of claim 1, wherein the puncturing feature is a sharp edge.
 5. The aerial projectile of claim 4, wherein the sharp edge has serrations.
 6. The aerial projectile of claim 1, wherein the puncturing feature is a machined feature of the wing.
 7. The aerial projectile of claim 1, wherein the puncturing feature is a separate part that is attached to the wing.
 8. The aerial projectile of claim 1, wherein the puncturing feature is comprised of a material selected from the group consisting of steel, stainless steel and tungsten carbide.
 9. The aerial projectile of claim 1, wherein the puncturing feature is comprised of a material having fine grain properties.
 10. The aerial projectile of claim 1, wherein the wing slot seal includes a burst seam.
 11. A precision guidance kit, comprising: a section of a fuselage having connectors on either end that are configured to couple to a projectile; at least one wing slot formed in the section; a wing slot seal covering each of the at least one wing slot; and a guidance wing being in a stowed position within each of the at least one wing slot prior to deployment of the wing, the guidance wing having a puncturing feature formed on a leading edge of the wing, the puncturing feature being configured to break through the wing slot seal during deployment of the wing from the stowed position.
 12. The precision guidance kit of claim 11, wherein the puncturing feature is formed on a tip of the wing.
 13. The precision guidance kit of claim 11, wherein the puncturing feature is a sharp point.
 14. The precision guidance kit of claim 11, wherein the puncturing feature is a sharp edge.
 15. The precision guidance kit of claim 14, wherein the sharp edge has serrations.
 16. The precision guidance kit of claim 11, wherein the puncturing feature is a machined feature of the wing.
 17. The precision guidance kit of claim 11, wherein the puncturing feature is a separate part that is attached to the wing.
 18. The precision guidance kit of claim 11, wherein the connectors are configured to couple to the projectile.
 19. The precision guidance kit of claim 11, wherein the wing slot seal includes a burst seam. 